Chemical elements
    Physical Properties
      Nickel Fluoride
      Nickel Dichloride
      Double Nickel Chlorides
      Nickel Dibromide
      Nickel Di-iodide
      Nickel Chlorate
      Nickel Perchlorate
      Nickel Bromate
      Nickel Iodate
      Tri-nickel Suboxide
      Nickel Suboxide
      Nickel Monoxide
      Nickel Dihydroxide
      Nickelo-nickelic Oxide
      Nickel Dioxide
      Nickel Subsulphide
      Nickel Monosulphide
      Nickel Sesquisulphide
      Tri-nickel Tetrasulphide
      Nickel Disulphide
      Nickel Tetrasulphide
      Nickel Sulphite
      Nickel Thiosulphate
      Nickel Dithionate
      Nickel Sulphate
      Nickel Subselenide
      Nickel Selenide
      Nickel Sesquiselenide
      Nickel Selenite
      Nickel Sesquitelluride
      Nickel Tellurite
      Nickel Chromate
      Nickel Dichromate
      Double Nickel Chromates
      Nickel Molybdate
      Nickel Nitride
      Nickel Azoimide
      Nickel Nitrite
      Nickel Nitrate
      Di-nickel Phosphide
      Nickel Sesquiphosphide
      Nickel Diphosphide
      Nickel Triphosphide
      Nickel Hypophosphite
      Nickel Phosphite
      Nickel Metaphosphate
      Nickel Orthophosphate
      Nickel Pyrophosphate
      Nickel Thio-orthophosphate
      Nickel Thiopyrophosphite
      Nickel Thiopyrophosphate
      Tri-nickel Diarsenide
      Nickel Arsenide
      Nickel Diarsenide
      Nickel Arsenite
      Nickel Orthoarsenate
      Nickel Antimonide
      Nickel Antimonate
      Nickel Thioantimonite
      Nickel Vanadate
      Nickel Carbide
      Nickel Tetracarbonyl
      Nickel Carbonate
      Nickel Monocyanide
      Nickel Cyanide
      Nickel Thiocyanate
      Nickel Thiocarbonate Hexammoniate
      Nickel Subsilicide
      Nickel Orthosilicate
      Nickel Monoboride
      Nickel Borates
    PDB 1a5n-1g2a
    PDB 1g3v-1mn0
    PDB 1mro-1s9b
    PDB 1scr-1xmk
    PDB 1xu1-2cg5
    PDB 2cqz-2jih
    PDB 2jk8-2v4b
    PDB 2vbq-3c2q
    PDB 3c6c-3h85
    PDB 3hdp-3kvb
    PDB 3l1m-3o00
    PDB 3o01-4ubp
    PDB 8icl-9ant

Nickel Sulphate, NiSO4

Nickelous Sulphate or Nickel Sulphate, NiSO4, has been obtained in various stages of hydration. Its solution is prepared by dissolving the hydroxide or carbonate in dilute sulphuric acid. When crystallised at 15-20° C., the heptahydrate, NiSO4.7H2O, is obtained as green rhombic prisms, isomorphous with the corresponding ferrous and zinc sulphates. Its density is 1.877, and specific heat 0.341.

Owing to its resemblance to ferrous sulphate or green vitriol it is frequently known as nickel vitriol. It is found in nature as the mineral moresonite. It effloresces in air, yielding the hexahydrate. At 100° C. it loses 4 molecules of water, and at 280° C. becomes anhydrous.

Its solution, evaporated at 50° to 60° C. or allowed to stand after addition of excess of dilute sulphuric acid, deposits crystals of the hexahydrate, NiSO4.6H2O. These are blue, tetragonal pyramids. The same hydrate is produced by prolonged exposure of the heptahydrate to air. This is an example of simple efflorescence, and is not dependent upon sunlight as was once supposed. If the crystals of heptahydrate occupy only a small portion of the containing vessel, they lose water with the formation of the hexahydrate, whether they are exposed to light or not. On the other hand, they are not changed, even by strong light, if the surrounding air is saturated with water vapour, or if the crystals are in contact with filter-paper moistened with turpentine, or if they completely fill the vessel containing them. The hexahydrate is also produced by prolonged exposure of the anhydrous salt to moist air (vide infra). The hexahydrate may further be obtained by leaving the heptahydrate for some hours in contact with its saturated solution at 32° to 53° C. The salt is dimorphous. At temperatures above 54° C. both the heptahydrate and the blue hexahydrate are rapidly converted into green monoclinic crystals containing 6 molecules of water.

The tetrahydrate, NiSO4.4H2O, has been prepared by crystallisation from a solution of the heptahydrate in sulphuric acid of density 1.4.

The dihydrate, NiSO4.2H2O, is formed from solutions by evaporation at temperatures above 118° C. It may also be obtained by the action of concentrated sulphuric acid upon the hepta- or hexa-hydrate. On heating the hexahydrate to 100° C., 5 molecules of wafer are expelled, the monohydrate, NiSO4.H2O, being produced. The same hydrate results when concentrated sulphuric acid is added to a solution of nickel sulphate, being precipitated from solution, and when a twice- normal solution of nickel sulphate is heated to 100° C. under a pressure of 100 atmospheres of air or nitrogen. At 280° C. the hydrated salts yield anhydrous nickel sulphate, which is yellow in colour. It absorbs moisture slowly from the air, yielding ultimately the hexahydrate, and in contact with water rehydrates itself, passing into solution if sufficient water is present. Density 3.643, specific heat 0.216. Heated to redness in air it yields nickel monoxide. Heated in a tube open at both ends it begins to decompose at 708° C. to the monoxide. Carbon reduces it to the free metal. A fifth-normal solution of nickel sulphate deposits metallic nickel at 186° C. under a pressure of 100 atmospheres of hydrogen.

It readily absorbs ammonia gas, yielding the hexammoniate, NiSO4.6NH3. If the anhydrous salt is dissolved in concentrated aqueous ammonia, however, a dihydrated tetrammoniate is produced, namely, NiSO4.4NH3.2H2O, which separates out in dark blue tetragonal prisms which are unstable in moist air.

The solubility of nickel sulphate in water at various temperatures is as follows:

Temperature ° C.0922.6303432.344.753.054.57099
Grams NiSO4 in 100 water27.2231.5537.9042.4645.543.5748.0552.3452.5059.4476.71
Solid phaseNiSO4.7H2ONiSO4.6H2O blueNiSO4.6H2O green

The transition points are as follow:

Heptahydrate ⇔ Blue hexahydrate + saturated solution [31.5° C.]
Blue hexahydrate ⇔ Green hexahydrate [53.3° C.]
Green hexahydrate ⇔ Dihydrate + saturated solution [uncertain]

Several Basic Nickel Sulphates have been described, but these are of less interest and importance.

Nickel sulphate yields numerous double salts. Of these the most important is Nickel Ammonium Sulphate, (NH4)2SO4.NiSO4.6H2O, which is largely used in electroplating. It is readily prepared by adding the requisite quantity of ammonium sulphate to a concentrated solution of nickel sulphate in dilute sulphuric acid. It crystallises in bluish green monoclinic prisms. These are less soluble than the corresponding cobalt salt.

Temperature ° C.3.51016203040506885
Grams of salt in 100 grams water1.

The corresponding Potassium, Rubidium, and Caesium salts have been prepared, and their crystallographic constants determined.

Anhydrous Nickel Ammonium Sulphate, 3NiSO4.2(NH4)2SO4, has been prepared by fusing together nickel sulphate, oxide, hydroxide, or carbonate and excess of ammonium sulphate. It combines with water evolving heat. When ignited, anhydrous nickel sulphate remains behind.

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